The Honda SL350 was the Japanese giants first attempt at a Dual Sport model. After a sticky start over 300,000 were sold in America in just 4 years and it helped pave the way for the genre in the decades to come.
Honda SL350 History
In the past, all motorcycles were made to be used on both pavement and unpaved roads because, in the early 20th century, the majority of road surfaces were frequently a complete mash-up of the two.
On a single short trip, you might start out on a gravel path, join a main paved road, and then quickly turn off onto a dirt track, or, if the weather gods had decided to play unfairly that day, mud.
As time and infrastructure progressed forward, more tracks and roads were paved and as such the motorcycle industry adapted to this change by producing bikes more exclusive to the hard stuff until eventually, specific cross-purpose machines were resigned to yesteryear.
A few manufacturers continued to offer “scrambler” models, but these were in essence the same road bike with slightly more dedicated tyres and a lifted exhaust.
For a while, this created a market void for dirt-focused bikes, into which Yamaha sprang in 1968 with the introduction of the DT1 250 trail bike. The days of making a half-hearted attempt at an off-road vehicle were long gone with the DT1’s meteoric rise to popularity and the rebirth of the Dual Sport category.
Honda, being on the back foot for once, responded with the release of the SL350 in 1969. The SL350 was a parts-bin special with the express purpose of capitalising on the dirt bike frenzy that Yamaha had ignited with the DT1.
However up against the dirt focused DT1 250, the heavy and under equipped SL350 had been thrown in at the deep end by Honda to do a job it wasn’t up to the task of fulfilling.
Honda SL350 Review
The Honda SL350 was a bike that evolved to defy its own first impression. When Honda unveiled the SL350 in 1969, the street-scrambler formula had lost its appeal. The production bike was overweight, over styled, and it had a tendency to throw riders off when the terrain wasn’t suitable for the bike. It just wasn’t up to the task that had been handed to it.
It was basically a CB350 with higher bars and a bit more ground clearance. The bike also weighed in at 165 kg, too heavy to take on the more difficult trails.
The 326 cc vertical twin cylinder motors were the exact same unit used across the CB and CL ranges; the same camshaft, same crankshaft, ignition, gearbox, etc. The sole difference was the final drive gearing.
The constant velocity Kehins’ weak return springs on the carburettor, couldn’t compensate for inertia or gravity properly, resulting in the SL350 detested big bumps and would immediately close when one was encountered which was inevitable with a suspension system that was designed for the road.
The Honda SL understeered excessively in fast turns, and the power came on a touch too quickly and sharply around the 5,000 rpm mark.
But the Honda SL350 had two qualities that everyone seemed to like: its spectacular looks and one of the most comfortable saddles ever. Nevertheless, the SL350’s reputation would not be saved by this. Simply put, it wasn’t what the off-road community sought, and it was quickly rejected.
In the wake of such a dismal response from the market and taking into account customer feedback. Honda went back to the drawing board to start over and do things right.
In comparison to its predecessor, the second generation SL350 K1 was virtually a brand-new machine when it was debuted in 1970. This was a dramatically improved machine.
The CB/CL series’ heavy single down tube frame was replaced with a brand-new, specially designed lightweight double downtube frame, which helped reduce weight by an incredible 27 kg. The engine remained the same, but the 30 mm CV units were changed with Kehin 24 mm carbs, which removed the 30 mm CV’s sliding problems that caused it to shut down on big bumps.
Further changes included a drastically altered camshaft enabled for maximum torque to be delivered higher up the rev range at 6,000 rpm. And although the more restricted exhaust system reduced the power from the CB’s initial 36 bhp to 30 bhp, the engine became considerably more useable.
No passenger footpegs were provided, Honda were serious that the SL350 was for solo off-road riding only. With increased trail, redesigned forks, smaller brakes, revised decent shocks and cast aluminium fenders completing the list of upgrades, the new SL350 K1 was everything a dual sport bike ought to be.
With the radical changes, the 1971 Honda SL350 had been completely transformed from a heavy, unyielding, unpredictable, unequipped off-roader into a nimble, user friendly, trail champion.
It was still heavy but was more manageable and was a small sacrifice to pay once you got it going. Thankfully, Honda’s gamble paid off, and the SL350, its previous transgressions pardoned, became the darling of the early dual sport period.
In 1972, the K2 model had a few minor alterations, such as the adoption of a 21-inch front wheel in favour of the previous 19-inch wheel (the 18 inch rear wheel would remain the same on all models), updated paintwork, and the inclusion of anodized metal fenders in place of painted ones.
The SL350 K2 was the last of Honda’s amazing trail twin with production coming to a halt in 1973. Despite over 300,000 being sold in the USA alone, making it one of the most popular motorcycles ever produced, Honda decided that with the rapidly expanding off road market it was no longer viable to run an essentially compromised design based on a road bike and a new dedicated machine was required.
In the latter half of 1972 the Honda XL250 Motorsport was introduced, which was designed to be the SL’s replacement. The single cylinder dual sport helped revive a subgenre that had all but disappeared during the British motorcycle industry’s decline.
It also helped expand the market that gave rise to revolutionary dirt motorcycles like the first Yamaha XT500 , the BMW R80G/S and of course, Honda’s own Africa Twin.
Honda SL350 Specs
Engine: Air-cooled, 2 valve, SOHC, parallel twin
Capacity: 326 cc
Max Power: 33 bhp / 9,500 kW @ 9,500 rpm
Max Torque: 26.4 Nm / 19.5 lb ft @ 8,000 rpm
Gearbox: 5-speed manual
Top speed: 86 mph / 138 kph
Fuel capacity: 9 L / 2.4 US Gal
Seat height: 840 mm / 33.1 inches
Wet weight: 145 kg / 320 lb
Buying an original Honda SL350
In the UK the SL350’s influence wasn’t quite as great as it was in the USA. Due to their scarcity, there are currently only a few of them for sale in the UK, and as a result, their prices have risen dramatically in recent years.
Currently you can buy this 1972 SL350 K2 with around 16,000 miles, completely restored for £4,489.
However, three years ago the same condition bike would have cost around £3,000.
The SL350 market in the USA is considerably different from that of the UK. Without really trying, I found over 30 different listings online. If we try to compare like for like, which is always difficult, the same condition bike for sale in the UK at £4,489 can be bought in the USA for around $3,500!
There are also several that would make wonderful restoration projects. The vehicle listed here is a nice example of one that has been locked away but is still in good cosmetic condition and could be put back on the road with little effort.
Restoring a Honda SL350
If you’re restoring an SL350 in the USA, you’ll have no problems finding any parts or need to worry about having it burn a hole in your wallet while you do, I was quite shocked at how affordable they are. A new headlight is just $28, and you can buy a complete piston for $50.
Both No Parts Now and Z1 Enterprises have a very good selection of SL parts in the USA.
Any UK restorers will struggle a lot more it seems. With very few places selling parts for the SL350. David Silver Spares Ltd seem to be the one place that had a good selection at reasonable prices.
Normally I’d wave the banner for the world’s favourite auction website but even there has a distinctive lack of parts in the UK. Alternatively, if you know all the parts you wanted then importing them might be the best option.
Is the Honda SL350 a good investment?
The SL350 is in short supply in the UK, and prices have already climbed by approximately 140% in the last three years alone. This trend is looking very likely to continue in the years to follow as well.
The UK is certainly an investors market for the little Honda at the moment due to its shortage of supply and understanding that the SL350 is gaining that classic bike status.
The USA as previously mentioned is a different market. The prices have stayed consistent with inflation in the past few years however that doesn’t mean the SL350 wouldn’t be a good investment.
Models that have been restored to an excellent showroom condition are still fetching between $6,000 – $10,000 so definitely worth a thought if you live on that side of the Atlantic.
I’m simultaneously annoyed and impressed by Honda for the SL350. I find it annoying that they essentially made a cheap imitation of a dual sport on the original SL to make a quick buck.
For me this goes against everything the company has mostly done over it’s long history.
However, I admire their resolve to not just scrap the project when it didn’t work but to double down and do things properly despite the huge risk they were taking as the motorcycle world could have assumed the worst based on the first SL and shunned the bike forever. So, kudos to Honda there, it seems things do balance out in the end.
I’d dearly like to get my hand on a Honda SL350, as a project would be my preference as well. When I’m not on the road, I’m UK based so this may pose a problem with the current availability on the market, but I always have a soft spot for old Honda dual sport motorcycles and the SL350 was the first in a long line of outstanding motorcycles that came after.
I’ll just have to wait patiently while keeping an eye on the market for the right one to come along.